DC / DC power supply: step-down converter
0.9 - 4 V | XC9509 Series Torex Semiconductor

The XC9509 series consists of a step-down DC/DC converter and a high-speed LDO regulator connected in parallel with the DC/DC converter's output. A voltage detector is also built-in. Since the input for the LDO voltage regulator block comes from the input power supply, it is suited for use with various applications.
The DC/DC converter block incorporates a P-Channel driver transistor and a synchronous N-Channel switching transistor. With an external coil, diode and two capacitors, the XC9509 can deliver output currents up to 600mA at efficiencies over 90%. The XC9509 is designed for use with small ceramic capacitors.
A choice of three switching frequencies are available, 300 kHz,
600 kHz, and 1.2 MHz.
Output voltage settings for the DC/DC and VR are set-up internally in 0.1V steps within the range of 0.9V to 4.0V (±2.0%). For the VD, the range is of 0.9V to 5.0V (±2.0%).
The soft start time of the series is internally set to 5ms. With the built-in UVLO (Under Voltage Lock Out) function, the internal P-channel driver transistor is forced OFF when input voltage becomes 1.4 V or lower.
The functions of the MODE pin can be selected via the external control pin to switch the DC/DC control mode and the disable pin to shut down either the DC/DC block or the regulator block.